Rockwell Automation 2755-G6-D Scanner with RS-232 Option - Manual (Page 82)

Serial Commands
Chapter 9
9–4
When the scanner is programmed for standby power
operation (@B), the first character of the command is
used to wake-up the scanner; it will not be recognized
by the scanner’s CPU. When there is any possibility
that the scanner is in standby mode, an extra space
code should be transmitted before STX to ensure the
scanner is awake before sending commands to it.
If you are not operating the scanner in standby mode,
the space has no effect on commands (space prefixed
commands are properly decoded).
Having sent the space code to wake-up the scanner, a
150 to 200 millisecond pause must be observed to
allow the scanner’s CPU to complete its initialization
tasks, during which time it is unable to accept serial
commands before issuing the programming
command. Failure to observe this delay causes the
scanner to ignore the incoming command.
All commands which affect serial communication are
acted upon immediately. When changing communi-
cation parameters (such as baud rate, word length,
parity), the scanner will send the ACK code, using
the newly implemented communication parameters.
There should be a delay after the host sends a
communication parameter setup command. This
delay allows the host computer to modify its internal
parameters and correctly receive the ACK code from
the scanner. This is due to the internal, one second
delay required for the scanner to update its internal
EEPROM.
Power Standby
and Serial
Commands
Communication
Parameter
Changes